I've got mixed feelings. Guest worker programs have a pretty troublesome history in Europe. However, there's some upped employer enforcement. Apparently we can get some path to citizenship in the House. If the guest work program has a path to citizenship, that's good enough for me. Without it, meh I'm hesitant to commit either way.
The key argument from Ezra is that this is best shot we'll have for a while. The President needs a victory and isn't worried about re-election. Future Democratic presidents have higher priorities (universal health care and such). The Republican debate also shows that with the exception of McCain future Republican presidents are less likely to be conciliatory.
If this doesn't pass, aid to Mexico is probably the only real way to try to do anything about it in the near future. Turning off the spigot would make comprehensive reform a lot easier. Right now, nobody trusts the enforcement measures and with fairly good reason.